1. Field of the Invention
The present invention generally relates to a cutting tool used in metalworking operations. More particularly, the present invention relates to a cutting tool for compressing a porous surface of a material to create a non-porous surface layer and thereafter removing a portion of the material to produce a desirable surface finish but to retain a portion of the non-porous layer.
Subsurface porosity exists in many materials, and the degree of such porosity is determined by the properties of the material itself and by the manner in which the material is fabricated (e.g., casting, powder densification, welding, etc.). For example, when two metallic parts must be mated to provide a seal for any fluids (e.g., gas or liquid) that may travel within the parts, it is very important for the subsurface porosity that is interconnected with the surface to be very low. However, there are instances in which this subsurface porosity is not low and, as a result, even though the parts may be properly mated, fluid escapes through or along the walls of the parts. Cast aluminum alloys are particularly susceptible to this problem. A tool is needed that is capable of sealing this subsurface porosity, at ambient and other temperatures, at least on the mating surface of the parts, and then, if necessary, machining this surface to obtain a desired surface finish while simultaneously retaining a layer of the non-porous surface.
A tool is therefore needed which is capable of sealing to a depth a part of or all of the surface of a workpiece having subsurface porosity and to then cut this surface to a lesser depth to provide a desired surface finish.
2. Description of the Prior Art
Japanese unexamined Published Patent Application No. 1-321101 teaches a cutting tool that is suited for cutting compound materials such as iron and aluminum in which the cutting tool has two cutting edges positioned along the length of one side of the tool whereby the first cutting edge is not honed but is sharp to cut the aluminum material, while the second following cutting edge is honed to cut the iron material. This design, however, does not address, nor does it provide a solution to the problem of materials having unacceptable levels of subsurface porosity.